Clamp



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M. STUPAR ET Aa.. ,3',5

CLAMP Filed may 1, `19:51

INVENTORS MAX STUPAQQ'V BY ATTORNEY GEORGE A PAGE Je,

Patented ocr. 11,` 1932 UNITED STATES PATENT OFFICE iuAx sTUPAE, OEBUFFALO, AND GEORGE A. PAGE, JE., or EBEEPOET, NEW Yonx, ASSIGN- ons rrooun'rrss AEEOPLANE a MOTOR COMPANY, ING., A CORPORATION OE NEW YORKOLAMP Application led Hay 1, 1931. Serial N0. 534,482. j

This invention relates to a clamp for metallic members and to one whichis especially vadapted for use in connecting tubes and other elementsused in aircraft construction.

Prior to our invention there has been generally used in the aircraftindustry a type of clamp known as the Fokker clamp. The

Fokker clamp is formed by welding to each-- end of a metallic strip ashort tube, thereby formin eyes through which a bolt may be inserteto'draw the two ends of the strip toward each other. The Fokker clampserves very well for its purposes but is extremely expensive to make.Inasmuch as it must be' welded, aluminum alloys are not absolutelysatisfactory for use in the Fokker clamp.

One of the objects of our invention is to provide a clamp useful inaircraft structures which is economical to produce and et issatisfactory for-all purposes for whlch it mi ht be desired.'

l further object is to reduce the weight of clamps used in aircraftstructure.

Further objects` will be apparent from a reading of the subjoinedspecification and claims and from a consideration. of the accompanyingvdrawing.

In order toexplain the invention more clearl one' embodiment thereof isshown in said rawing, in which: j .g

' Fig. 1 is a perspective view 'of a clamp constructed according to 'my'invention shown embracing a relatlvely large tube, the clamp beigifastened tightly around said tube by a o t Fig.,2 is an end view of aclamp of slightly diferent construction separate from any structure towhich it might be attached shown partly in section; and

Fig. 3 is a side view of the clamp shown in Fig. 2.

'Re erring in detail to the drawing, we have shown in Figs. 1, 2 and 3two clamps of slightly different design lbut have used the samereference numerals to designate simi-y lar elements. We have shown inFig. 1 a relatively large tube 11 to which is attached a clampconstructed accordin to our improved design and generally esignated 12.This clamp is formed of a strip 13 of suitable metal, preferablyduralumin, the ends of which are die-pressed to form the cu shapedprojections 14 and 15. As may e seen more clearly in Figs. 2 and 3 thepro-4 jections 14 and 15 are formed with holes such as the holes 17 and18 through which .a bolt such as the bolt 19 is adapted to be inserted.A castellated nut 21 is threaded upon the end of the bolt 19 and acotter pin 22 is used to lock the nut.

l Tubes and other elements may be secured to the clamp by weldin ifdesired. In Figs. 2 and 3 are shown simp e clamps without any other artwelded thereto. In Fig. 1, however, t ere is shown a small tube 23welded o5 to the side of the stri 13 so that the tube 23 extendssubstantia y at right angles to the strip 13. Otherwise the clamp shownin Fig. 1 1s exactly the same as that shown in Figs. 2 and 3.

In the process of forming our im roved clamp, a strip of metal is out tothe esired shape and length and the ends of the strip are die-pressed soas to form hollow projections Of substantial thickness and of threesidedformation whereby the ends of the strips may be attached to each other.It is to be especially noted that the projections 14 and 15 are notsimple right angled projections but are more or less cup-shaped andthereby -ap licant isenabled to obtain anchors of su stantial strength.Theholes 17 and 18 are unched through the ends of the strip after t erojections have been formed. Any desired tting, tube, bracin member orother structural member may welded to the clamp as is the tube 23 in theillustration'of Fig. 1. or the clamp may be used withl out having anyotherelement weldedithereto a bell crank lever) moves the portions ofthe main strip 13 which are adjacent to the proections and 26 away fromthe tube 1l and thus tightens the rest of the clamp around the tube. Itmay thus be seen that the construction of the invention involving as itdoes the cup-shaped end projection 1s entirely dierent in`its actionfrom the action of a mere strip fastened around a tube. The stressesinvolved iiithe action of a clamp designed according to this inventionbecome largely compressive stresses rather than purely bendingstresses.. The two sides of the cups are pressed against each other andfurther tightening of the bolt acts in compression wlth these sides andretards the bending at the base of the projections.

Prior to the development of this improved form of clamp, we designedanother form in which the ends were also formed with cupshapedprojections. The earlier form, however, difered from the form shown inFig. 2 in that the ends thereof instead of slanting f as shown at 31 and320i Fig. 2 slanted out`- ward toward each other. By the construction ofour. earlier design, tightening of the clamp by means of a bolt broughtthe outer ends of the rojections into contact with each other and urthertightening of the ,clamps caused said outer ends to form the fulcrum ofa lever in which the bolt served for the application of force and themain portion of the strap received the work done by the application ofthe force. While the earlier form of our invention enjoys some of thesame advantages as the latter in that it uses cup-shaped projections andconverts bending stresses into compression stresses, yet the formillustrated and claimed' herein is believed to be much superior. f l Asmay be clearly seen in Fig. 1 there are left on each side'of the'cupprojections fiat surfaces such as 27, 28 and 29 which contact with thetube to be embraced and thus minimize the danger of a sharpedge piercingthe thin walls of the tube to be embraced.

The construction'shown is very strong. It approximates the constructionof the prior art clamps in strength, but hardly compares with them incost, inasmuch as the cost of our improved clamp is only from 1/ 15 to1/25 of the cost of the rior art clamps. It is adequately strong or thepurposes desired, inasmuch as the threads will be stripped from the bolt before any part of the clamp fails.

A further advantage of our improved clam is that if desired the holes 17and 18 j may e placed as shown so far inward that they bring the shankof the bolt adjacent to the tube to be embraced. Inasmuch as the momentat the pressed boss depends on the length of the lever arm between thepoints 25 and 26 and the bolt 19, this moment may formed upon said band,one each at opposite ends thereof, said projections being disposed withtheir open sides adjacent and having each an overall width substantiallyless than the width of said band at saidvends; and means passing throughsaid projections and bearing thereon for drawing the ends of said bandtogether.

2. A clamp for aircraft use comprising a sheet metal band adapted toencircle a structuralelement of the aircraft, substantially cup-shapedopen'sided projections formed on and from said band, one each atopposite ends j thereof, said projections being disposed with their opensides adjacent and each having an overall width substantially less thanthe width of said band at said ends, and means passing through said opensides and said proj ections and bearing thereon fordrawing the ends ofsaid band tovether. f

3. A clamp for aircraft use including a ilat bearing strip initially ofequal width throughout itslength, having formed on and from said striptoward the ends thereof projections, each said projection comprising ape'rforate portion substantially' at right angles to said strip, bracketportions substantially normal to said perforate portion, eX-

tending toward and merging into the end of said strip, the 'unctures ofsaid bracket portions with sai strip of the two projections beingsubstantially adjacent when said clamp is curved about a member of saidaircraft, and means engaging said perforate portions for drawing theends of said strip together, the overall width of said bracket portionsbef ing less than the width of said flat strip at the ends thereof. v

In testimony whereof vwe hereunto aflix our signatures.

MAX STUPAR. I GEORGE A. PAGE, JR.

thus be reduced to a minimum. This fact toj f gether with the ability touseduralumin-alloys

